Vital capacity correlates with respiratory muscle function in AMD. Diaphragm weakness is the major cause of SDB and RF. SDB and nocturnal hypoventilation are predictable from daytime function tests.

The aim of the current study was to investigate the long­term impact of nocturnal noninvasive (positive­pressure) ventilation (NIV) on sleep, sleep­disordered breathing (SDB) and respiratory function in children and adolescents with progressive neuromuscular disorders (NMD).Thirty patients (12.3±4.1 yrs) with various inherited NMD were treated with NIV for ventilatory insufficiency (n=14) or symptomatic SDB (n=16). Patients were prospectively followed with sleep studies, spirometry and peak inspiratory muscle pressure. Ten patients were studied before and after 3 nights withdrawal from NIV.NIV normalised nocturnal gas exchange in all patients and diurnal gas exchange in patients with ventilatory insufficiency. The effects persisted over 25.3±12.7 months. Nocturnal transcutaneous partial pressure of carbon dioxide improved from (baselineversuslatest control) 7.1±1.3 to 5.5±0.6 kPa (53.7±9.9 to 41.6±4.8 mmHg), diurnalcarbon dioxide arterial tension from 6.3±1.6 to 5.4±0.5 kPa (47.5±11.9 to 40.6±3.6 mmHg).NIV improved respiratory disturbance index, arousals from sleep, nocturnal heart rate and sleep architecture. Vital capacity decreased in five adolescents with Duchenne muscular dystrophy −183±111 mL·yr−1but remained stable in 25 children with other conditions (8±78 mL·yr−1). Three nights withdrawal of NIV in 10 previously stable patients resulted in prompt deterioration of SDB and gas exchange back to baseline but could be instantly normalised by resumption of NIV.Noninvasive (positive­pressure) ventilation has favourable long­term impact on nocturnal and diurnal gas exchange and sleep and in patients with non­Duchenne neuromuscular disorders on vital capacity as well. It is indicated in children and adolescents with symptomatic sleep­disordered breathing or ventilatory insufficiency due to neuromuscular disorders.

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IVC(S) correlates with respiratory muscle function, daytime and nocturnal blood gases, and is highly predictive of SDB and daytime hypercapnia.

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